The Nanotube Battery

NEC has used carbon nanotube technology to build a fuel cell with 10 times the energy density of today's most advanced batteries, which could be used for powering mobile phones and portable computers.

Working with the Japan Science and Technology Corporation and the Institute of Research and Innovation, NEC has used one type of nanotube, a 'carbon nanohorn', to construct the electrodes in the fuel cell.

NEC has been working on the technology since the discovery of the tube-like structures by one of its research fellows,
Sumio Iijima, in 1991. He extended the work to the nanohorns three years ago.

The main characteristic of the carbon nanohorns is that when they group together an aggregate (a secondary particle) of about 100nm is created. This creases an electrode with a very large surface area where gas and liquid can permeate, increasing the efficiency of the polymer electrolyte fuel cell developed at NEC. The nanohorn structure also means that smaller particles platinum can be used as a catalyst, again giving greater efficiency and increasing the reliability of the cell.

The solid type polymer cell, based around a fluoride polymer film as an
electrolyte, operates at room temperatures unlike other fuel cells and is also
lightweight, with an energy-conversion efficiency of 50%; more than double that
of today's batteries.